Debugging messages can be included in NSE scripts using the debug() function from the stdnse library. These messages are shown only when the debugging level has been set to a value higher than 0:

Debug(level, fmt, …) where
level: Debugging level.
fmt: Format string.
…: Format arguments.

To print a debug message when the debugging level is 1 or higher, we use the following code:

stdnse.debug(1, "Task #%d completed.", id)

The idea behind supporting this function is that we can do things such as printing different levels of information without having to write nested code:

stdnse.debug(1, "Response #%d received.", i)
stdnse.debug(2, "Response status code: %d", req.status)
stdnse.debug(3, "Response body:", req.body)

It is important to provide some debugging information in all your NSE scripts. This helps people figure out why things go wrong and submit bug reports.

$ nmap –d3 --script mybuggyscript &lt...